Well if you really do need the extra 4GB RAM and a 160gb SSD you might aswell pay the difference instead of installing it yourself.
Since a 160gb SSD will cost about ~$250. And the RAM would be like 30-50$ I guess.
So I guess it is worth the money to just get the A2 if you actually do indeed need the SSD and extra 4GB of RAM.

A suggestion ... don't buy off the shelf. Look into customizing your model. I suggest XOTICPC. Service is amazing. There are a number of other online retailers as well. I ordered my Sager and it arrived 8 days later ... and I had it shipped to Taiwan. Very fast.